Apparatus for blow molding hollow containers



May 9, 1967 Y P. T SCHURMAN ET AL 3,317,955

APPARATUS FOR BLOW MOLDING HOLLOW CONTAINERSv ATToRNqgs.

May 9, 1967 P. T. SCHURMAN E? AL 3,317,955

APPARATUS FOR BLOW MOLDING HOLLOW CONTAINERS Filed Dec. 2l, 1964 2Sheets-Sheet 2 4*? suPPL Y `5 7 77Z r d@ ggg caws rm? coN-rrzog 5 7 427Z INVENToRs Per TSc-'Zvar'marz cme l BY Fay/wand C Cmr ATTQPNEYS.

AUnited StatesPatent Office 3,317,955 Patented May 9, 1967 3,317,955APPARATUS FOR BLOW MOLDING HOLLOW CONTAINERS Peter T. Schurman, Snyder,and Raymond C. Confer, Gasport, N.Y., assignors to W. R. Grace & Co.,New York, N.Y., a corporation of Connecticut Filed Dec. 21, 1964, Ser.No. 420,023 9 Claims. (Cl. 18-5) l This application is acontin-uation-in-part of our pending application Ser. No. 369,159 filedMay 21, 1964.

This invention relates generally to the blow molding of thermoplasticmaterial, and more specically to a new and useful apparatus for blowmolding thermoplastic articles. While not limited thereto, our inventionis particularly concerned with the molding of plastic containers ofone-piece construction having a body part and a cover part hingedthereto, of the type disclosed in said application Ser. No. 369,159.

Heretofore such containers have been injection molded, producing aone-piece construction which is relatively flimsy and relativelyexpensive as compared to containers using steel or other non-plasticmaterial. As a result, such containers have not achieved their fullpotential.

A primary object of our invention is to provide a method of andapparatus for molding plastic containers of one-piece constructionhaving hinged -body and cover parts which are substantially stronger andmore rigid than prior art constructions of this general type.

Another object of our invention is to provide an apparatus for molding aone-piece plastic container having hinged body and cover parts at leastone of which is of double wall construction.

It is also an object of our invention to provide an apparatus formolding a one-piece plastic container having hinged body and cover partsat least one of which has a double wall construction, wherein eitherwall can be changed independently of the other.

In carrying out our invention in one aspect thereof, the two hingedparts of a container are blow molded, to form a double walled envelopefor each part. One side of the envelope comprises an exterior wall ofone side of the part while the other side of the envelope forms aninterior wall thereof. This is accomplished by closing complementarymold parts about a tubular extrusion of molten plastic material, themold parts having portions coacting to provide a pair of adjacentcavities. The parts forming the interior walls project into the cavityparts forming the exterior walls, leaving sufcient space for blowmolding the desired double wall structure. As the mold parts close theypinch the extrusion around the cavities to form the meeting edges andsimultaneously form a connecting hinge by complementary parts extendingbetween the two cavities.

However, a problem arises when the interior wall forming parts approachthe exterior wall forming parts too closely, because that portion of theextrusion intended to engage the exterior wall forming part has atendency in its molten state to collapse inwardly against that portionof the extrusion which is being forced into the cavity by theprojecting, interior wall forming part, whereupon the desired structurecannot be formed.

Therefore, another object of our invention is to provide a means forcontrolling the tubular extrusion as the mold sections are broughttogether, to prevent undesired collapsing of the tubular walls againsteach other.

Another problem arises in providing a hinge having sufficient fatiguelife. The mold is cooled to set the tubular extrusion as the moldsections are engaged thereabout. While the resulting double wallenvelopes comprising the hinged parts have a flex life sufficient forthe intended purpose, the hinge is subject to stresses and strains whichtend to materially reduce its useful flex life.

Therefore, another object of our invention is to provide a means wherebythe stresses and strains in the hinge section are relieved during themolding process, to produce a longer lasting hinge.

Another object of our invention is to provide an extrusion dieespecially adapted for the molding of articles by the method of ourinvention, the die containing parts which can be adjusted or changed tovary the wall thickness of the extruded parison.

In one aspect thereof, molding apparatus of our invention for forming athermoplastic container having mating parts joined by a hinge ischaracterized by the provision of means for forming a tubular parison ofthermoplastic material, mold sections adapted to be moved intoengagement about the parison, the mold sections when engaged forming apair of cavities one of which has the shape of one container part andthe other of which has the shape of the other container part, the moldsections engaging the parison on opposite sides thereof to pinch andweld the same between the cavities, thereby providing the hinge anddividing the parison into a pair of hollow sections within the cavities,together with means for introducing fluid into the parison sections toexpand the same into conformity with the respective cavities.

The foregoing and other objects, advantages and characterizing featuresof the apparatus of our invention will become clearly apparent from theensuing detailed description thereof, considered in conjunction with theaccompanying drawings wherein like reference numerals denote like partsthroughout the various views and where- FIG. l is a vertical sectionalview through an extrusion die of our invention;

FIG. 2 is a vertical sectional view thereof, taken about on line 2-2 ofFIG. 1;

FIG. 3 is a bottom plan view thereof;

FIGS. 4 and 5 are corresponding, fragmentary detail views of modifiedextrusion die constructions;

FIG. 6 is a vertical sectional view, on an enlarged scale, throughmolding apparatus of our invention, showing the mold sections closedabout a tubular parison to form a hinged container in accordance withthe method of our invention; and

FIG. 7 is a schematic layout of a complete apparatus of our invention.

Referring now to the accompanying drawings, there is shown apparatus lofour invention for molding a hinged thermoplastic container of the typeillustrated and described in our aforesaid application Ser. No. 369,159.As shown in FIG. 6, which corresponds to FIG. 5 of our said applicationexcept that the container is inverted, this being the preferred moldingposition, the container comprises mating parts 1 and 2 joined by a hinge3 integral therewith. Part 1 comprises a relatively deep body part ofhollow, double wall construction formed by an outer shell havingopposite end and side walls 4 and a bottom wall 5, and an inner shellhaving opposite end and side walls 6 and a bottom wall 7. Side and endwalls 4 of the outer shell are joined to the side and end walls 6 of theinner shell by a peripheral flange in the form of a ledge 8 completelyencircling the inner shell. An upstanding rib 9 is formed on led-ge 8,for indexing purposes.

In like manner, part 2 comprises a relatively shallow top cover part ofhollow, double wall construction having an outer shell formed byopposite end and side walls 11 and a bottom wall 12, and an inner shellformed by opposite end and side walls 13, and a bottom wall 14. Theinner and outer side and end Walls 13, 11 are joined l by a peripheraliiange in the form of an inwardly offset ledge encircled by a skirt 16and completely encircling the inner shell.

Of course, parts 1 and 2 can be of the same size, and part 2 can belarger or deeper than part 1, if desired.

In accordance with our invention, body and cover parts 1 and 2 aremolded integrally with hinge 3, in one piece, this being accomplished bya blow-molding operation las follows:

Molten plastic material, not shown, is fed into an extrusion die 17 byconventional feed means, not shown, from a suitable supply (FIG. 7). Theextrusion die 17, as shown in FIGS. l-3, includes a die body 18 havingan inlet opening 19 through one side, the opening 19 communicating witha vertical bore 20 opening downwardly through die body 18. Preferablybore 20 is not circular, as is conventional, but is laterally elongated,having generally parallel flat sides and curved ends.

A mandrel 21 is positioned in bore 20, the upper portion of the mandrelhaving a sliding iit in bore 20 and the lower portion of the mandrelhaving a cross sectional configuration generally concentric with body 18Iaround bore 20 and spaced therefrom to define a tubular extrusionpassage. Mandrel 21 is positioned in bore 20 as by bolts 22 which extendthrough the upper end of die body 18 and are threaded into the upper endof mandrel 21 on opposite sides of a bolt valve 23 to be described.Mandrel 21 has a lateral passage 24 therethrough, comprising acontinuation of inlet passage 19. Also, the upper portion of mandrel 21has downwardly opening recesses 25 of downwardly diverging side wallfor-m on opposite sides thereof, communicating with passages 19 and 24and with the tubular extrusion passage along the elongated sidesthereof.

Raw material fed through inlet opening 19 is held at plasticizingtemperature by means such as cartridge-type electric heaters 26, of atype known in the art, positioned in body 18. The heated die body causesthe thermoplastic material to remain molten, and semi-Huid, and thissemifluid material flows into the upper end of bore 20. Some of themolten material flows through the recess 25 immediately adjacent passage19, downwardly along the near side of the mandrel, while some moltenmaterial fiows through mandrel passage 24 to the far recess 25, wherebythe molten plastic material is caused to surround mandrel 21 and movedownwardly therealong. The lower portion of mandrel 21 is spaced fromthe side wall of the bore 20 to define a tubular extrusion passagewaywhich fills with the molten thermoplastic material to extrude a tubularparison 27 of laterally elongated, fiat-sided form.

The extrusion of a laterally elongated, flat-sided parison offers manysuch advantages. Such a tube tends to be non-directional, unlike acircular tube, and furthermore has the aproximate shape of the containerto be molded as shown in FIG. 6. If a circular tube were used, anundesirably large dia-meter often would be required.

The iow of molten plastic through the mandrel passage 24 can beregulated by bolt valve 23 which is threaded in the upper end of diebody 18. Bolt 23 has a rotary valve end 28 extending through the upperend of mandrel 21 into the passage 24 for variably restricting the same.

The cross-sectional shape and wall thickness of the parison 27 isdetermined by a plate 29 mounted on the lower end of mandrel .21 whichis recessed immediately above the plate, as indicated at 30. Plate 29 issecured to mandrel 21 as by screws 31, whereby it can be detached andreplaced by a plate of different configuration. In this way, parisons ofdifferent wall thicknesses can be extruded from a single die 1-7.

Instead of a removable plate 29 coacting with a fixed wall of bore 20,the lower end of the mandrel can be fixed and permanent, with the diebody having a removable insert 32 f-orming the lower end of the borewall as shown in FIG. 4. Insert 132 can be detachably secured in placeas by bolts 33 for replacement by an insert of 4 different configurationto provide an extrusion of different side wall form.

Plate 29 and insert 32 can be designed to provide an extrusion vhavingdifferent wall thicknesses therearound. In FIG. 3, for example, one side32 of the extrusion passage is approximately twice as wide -or thick asthe opposite side 33. In addition to providing opposite side walls ofdifferent thicknesses, a given side wall can have portions of differentthickness by appropriately recessing or embossing either the removableplate 29 or the removable rim insert 32.

Also, the extruded parison 27 can be provided with axially spacedsections of different thickness. This can be accomplished, for example,by providing a die body 1S (FIG. 5) having an undercut inner wall 34 atthe lower end of extrusion bore 20. The mandrel 21 has a plate 29 whichcan be detachable and which projects beneath the overhang of wall 34. Byproviding the mandrel with lift jacks as indicated at 35 (FIG. 7)actuated by hydraulic-pneumatic, or other forms of motor indicated at 36the mandrel can be raised and lowered to vary the spacing between theplate 29' and wall 34. This will vary the wall thickness of the parisonas it is extruded. In accordance with our invention, the extrudedparison 27 is passed between paired mold sections generally designated37, 38 which are mounted for movement into and out of engagement aboutparison 27. Mold sections 37, 38 can be pivotally mounted or otherwisesupported and can be moved by conventional drive means 39.

Mold section 37 comprises a plate section, having a body 40 andremovable cores 41, 42. Core 41 is mounted in a recess in body 40, theportions of the core projecting from body 40 having surfaces definingthe inner wall, ledge and rib portions 6, 7, 8 ,9 and 10 of the innershell of container body part 1. Core 42 is mounted in another recess inbody 40, and its projecting surfaces are formed to define the innershell portions 13, 14 and 15 of container cover part 2. Mold section 38is recessed to define the outer shell portions of container parts 1 and2.

Thus, mold sections 37, 38, when engaged, define a pair of cavities. Onecavity has the shape of one container part, and the other cavity has theshape of the other container part. Mold section 38 defines the outershell configuration of the molded article, and mold section 37 the innershell configruation thereof. It is a feature of our invention that theconiiguration of either inner shell can be changed without changing theconfiguration of the other and without changing either outer shellconfiguration. This is accomplished by removing the appropriate core 41,42, which are simply bolted in place from behind, through body 40, andreplacing it with another core having the desired configuration.

Mold section 38 and body 40 are provided with opposed land portions 43,44, respectively, which are arranged to pinch the parison between them,welding the opposite side walls of the parison together and forming thehinge 3. Mold section 38 also is provided with a knife-edge formation45, extending completely around the cavities except at the hinge andadapted to engage against the mold body 40 as a bed plate for pinchingand severing the enclosed parison portion.

Thus, upon closing mold sections 37, 38 about the parison 27, a portionthereof is enclosed. The mold sections pinch oii the enclosed portion,and simultaneously pinch form the hinge 3, thereby dividing the enclosedparison portion into a pair of hollow sections positioned within themold cavities and separated by hinge 3. Mold section 37 carries meansfor introducing expansion iiuid into each hollow parison section, suchmeans comprising a pair of needles 46 which are mounted in section 37and project beyond the cavity defining faces thereof through the wall ofthe enclosed parison. A source of compressed air is connected viaconduit 47 to each needle 46, for introducing compressed air into eachof the hollow parison sections, thereby expanding them into engagementwith the cavity walls, causing the parison sections to assume the shapeof the cavities. Cores 41, 42 and the mold 38 are cooled, as by coolingwater ducts 48 connected to a suitable source of cooling uid. This coolsand sets the molded plastic, causing it to retain the moldconfiguration.

Thus, with the method and apparatus of our invention there is provided aone-piece plastic container having mating parts joined by an integralhinge, all in a single blowmolding operation. The resulting containerhas many advantageous features, as pointed out for example in ourapplication Ser. No. 369,159 to which reference is hereby made foradditional details concerning the container itself.

Where a single wall construction is desired, the inner shell of eitherpart 1, 2 can be either wholly or partially removed, as by severing witha circular cutting saw. Preferably, this is done by cutting through theside and end walls 6, 13, as the case may be, as described in our saidapplication with reference to FIG. 4 thereof.

It is a particular feature of our invention that the plastic parison canbe pinched very thin by the knife edge 45 easily and without using greatforce. In accordance with our invention, mold body 40 is heated, as bycartridge heating elements 49, in the area against which the knife edgeformation 45 engages. The heated body 40 maintains the parison at ornear its plasticizing temperature and therefore in a molten, semi-fluidcondition at the area of pinching, as the mold sections close, wherebythe weight of the molds themselves is suliicient to cut almost throughthe plastic. This is accomplished during the blow molding operation,without requiring special cutting equipment or the tons of forcerequired to pinch off a cooled plastic.

It is afurther feature of our invention that a hinge of long flex llifeis provided, notwithstanding the cooling of the expanded parisonsections in the mold. This is accomplished by heating the land 44 to atemperature maintaining the pinched hinge web in a semi-fluid conditionlong enough to relieve stresses and strains set up in the pinched hingeweb.

It will be noted that mold section 37 is simultaneously heated in partand cooled in part. Therefore, cores 41, 42 are substantially insulatedfrom tbody 40. This is accomplished by bevelling or tapering the sidewall portions of the cores 41, 42 `away from the side walls of therecesses in which they are seated, as shown at 50, and by spacing theinner faces of the cores from the bottom walls of the recesses, therebyproviding insulating dead air spaces between body 40 and the coreportions seated in the recesses. Further, the spaces between the innerfaces of cores 41, 42 and the bottom walls is lled with heat insulatingand/or dissipating spacing material, such as the wire screening 51. As aresult, cores 41, 42 contact body 40 only adjacent the outer edges ofthe recesses, and the desired heating of body 40 does not interfere withthe desired cooling of cores 41 and 42.

It will be appreciated that the illustrated arrangement of cooling ducts48 and heaters 49 is schematic, and that the salme are provided insufficient numbers and at proper locations to achieve the desiredresult.

In the illustrated container, the inner shells of the parts 1 and 2approach the outer shells thereof very closely. Indeed, they are weldedtogether at spaced locations 52 for added reinforcement as described inour aforesaid application, although this need not necessarily be done.Where welding is desired, the cores 41, 42 are shaped accordingly.However, a problem of undesired welding together Iarises because of theclose positioning of the inner and outer shells. There is a tendency forthe parison portions 5, 12 to fall away .from the mold 38 and collapseagainst portions 7, 14 las the mold sections close about the lparison.If this occurs, at any point, the opposite wall portions of the parisonweld together, preventing subsequent expansion in the mold cavity.Therefore, it is a particular feature of our invention that means areprovided for controlling those portions of the parison intended toengage the recessed cavity faces, the opposite 6 parison por-tions beingmaintained under projecting cores 41, 42.

The desired control is provided by evacuating or withdrawing air frombetween the cavity faces of mold section 38 and the adjacent wallsections of the enclosed parison. This can be accomplished in variousways. In the illustrated embodiment, air is withdrawn from between theplastic wall section 12 and the adjacent cavity face of mold section 38through vacuum passages 53 which are of extremely small diameter, forexample .03 inch, and which communicate with a manifold passage 54through the mold section 38. Manifold passage 54 communicates with anappropriate source of suction through a conduit 55. In the case of theouter shell of container part 1, the wall portion 5 thereof is definedin part :by a removable insert plate 56 mounted on the mold section 38from behind, as by bolts or the like. Plate 56 is provided with `aslight clearance therearound, between it and the surrounding portion ofmold section 38, this clearance being indicated at 57 and being on theorder of .O1 inch. The rear face of plate 56 is provided with transversegrooves extending between the opposite edges thereof, in generally rightangular relation, as indicated at 58 and 59, for placing the clearance57 in communi-cation with the manifold passage 54, through theconnecting passage 60.

Thus, as the mold sections 37, 38 are closed about the parison, air iswithdrawn from between the parison tand the cavity faces of -moldsection 38. A strong suction source is not essential. All that isrequired is to relieve the pressure of air trapped between the parisonand the cavity faces of mold section 38, which trapped air otherwiseprevents the 4parison from following the contour of the mold section 38as the mold sections are engaged about the parison. The clearance space57 and passages 53 are so small as to preclude the passage of plastictherethrough, while being suflicient to permit the desired withdrawal ofair. Such withdrawal takes place as the mold sections 37, 38 close aboutthe extruded parison, prior to the introduction of expansion fluidthrough needles 46. The introduction of expansion fluid causes theparison envelopes to expand into conformance with the surface definingfaces of their respective cavities, undersired inward collapsing of theparison wall being avoided fby such expansion. Also, it will beappreciated that the oblong, flat sided shape of the parison,approximating the outline configuration of the container in its openposition, assists in providing a controlled expansion of the hollowparison sections within the lcavities.

The feeding of the raw plastic material, the opening and closing of themold sections and the heating and cooling thereof, the withdrawal of airfrom between the parison and mold section 38 `and the introduction ofexpansion fluid all are controlled by suitable programming means, whichalso can control the lifting and lowering motor 36 connected to theextrusion die mandrel. Such controls are conventional, in and ofthemselves, and therefore are only schematically indicated in FIG. 7.

In addition to forming the hinge 3, mold sections 37, 3-8 can bearranged to form a fastener tongue 17 having an enlarged head 18 asdisclosed in our said application Ser. No. 369,159, and a flange 61corresponding to the flange 20 of said application and adapted forinterlocking engagement with the fastener tongue 17 in the manner setforth therein.

Accordingly, it is seen that our invention fully accomplishes itsintended objects. The means of our invention can be used lwith anysuitable thermoplastic material, such as high density polyethylene,polypropylene, polyvinyl and elastomeric polyolen, which are given byway of example only. While we have disclosed and described in detailprimarily only one embodiment of our invention, with certainmodifications of the extrusion die, it will be appreciated that this hasbeen done yby way of illustration only, without thought of limitation.

Having fully disclosed and completely described our control by theinvention, together with its mode of operation, what we claim as new is:

1. In blow molding apparatus for forming a thermoplastic containerhaving mating parts joined by a hinge with each part being of hollowdouble wall construction, means for forming a tubular parison ofthermoplastic material, mold sections adapted to be moved intoengagement about such parison, said mold sections when engaged forming apair of cavities one of which has the shape of one of the containerparts and the other of which has the shape of the other of the containerparts, said mold sections also engaging the parison on opposite sidesthereof to pinch and weld the parison between said cavities therebyproviding the hinge and dividing the parison into a pair of hollowsections within said cavities, and means for introducing uid into theparison sections to expand the same into conformity with the respectivecavities.

2. In blow molding apparatus vfor forming a thermoplastic containerhaving mating parts joined by a hinge, each of said parts being ofhollow double wall construction, an extrusion die capable of forming adownwardly extending tubular parison when thermoplastic material in amolten semi-uid condition is forced therethrough, a pair of moldsections adapted to be moved inwardly about such parison into engagementwith each other, said mold sections when engaged forming a pair ofcavities one having the shape of one of said container parts and theother having the shape of the other `of said container parts, said moldcavities being separated by lands on said mold sections which engage theparison on opposite sides thereof to pinch and weld the parison betweensaid mold cavities thereby providing said hinge and dividing saidparison into a pair of hollow sections within said mold cavities, andmeans for introducing uid into said parison sections to expand the sameinto conformity with the respective mold cavities.

3. In blow molding apparatus for forming a thermoplastic containerhaving mating parts joined by a hinge, each part being of hollow doublewall construction, means for forming a tubular parison of thermoplasticmaterial, mold sections adapted to be moved about such parison intoengagement with each other, said mold sections when engaged forming apair of cavities each having opposing faces, the opposed faces of onecavity defining the inner and outer walls of one container part and theopposed mold faces of the other of said cavities delining the inner andouter walls of the other container part, said mold sections engaging theparison on opposite sides thereof to pinch and weld the parison betweensaid cavities thereby providing the hinge and dividing the parison intoa pair of hollow sections within said cavities, and means forintroducing uid into the parison sections to expand the same within therespective cavities.

4. In blow molding apparatus for forming a thermoplastic containerhaving mating parts joined by a hinge, each part being of hollow doublewall construction, means for forming a tubular parison of thermoplasticmaterial, a pair of mold sections adapted to be moved into engagementabout such parison, said mold sections when engaged forming a pair ofcavities one having the shape of one container part `and the otherhaving the shape of the other container part, the cavity faces providedby one of said mold sections dening the outer walls of both containerparts and the cavity faces provided by the other of said mold sectionsdefining the inner walls of both container parts, said mold sectionspinching and welding the parison between said mold cavities therebyproviding the hinge and dividing the parison into a pair of hollowsections within said mold cavities, and means for introducing fluid intothe parison sections to expand the same into conformity with therespective mold cavities.

5. Apparatus as set forth in claim 4, together with means forwithdrawing air from between the parison and a portion of the cavityfaces provided by said one mold section to hold the parison thereagainstprior to the introduction of expansion fluid into the parison sections.

6. Apparatus as set forth in claim 4, wherein a portion of a cavity faceprovided by said other mold section projects into the correspondingcavity face provided by said one mold section, together with means forevacuating air from between the parison and said corresponding cavityface to hold the parison thereagainst prior to the introduction ofexpansion fluid into the associated parison section.

7. Apparatus as set forth in claim 4, where a portion of the cavityfaces provided by said other mold section project into the correspondingcavity faces provided by said one mold section, said other mold sectionincluding a body and cores mounted on said body, said cores providingsaid projecting cavity face portions, means for cooling said cores andsaid one mold section, and means for heating said body of said othermold section.

8. Apparatus as set forth in claim 7, wherein said mold vsection bodyhas recesses receiving said cores, the core portions within saidrecesses being spaced from the walls thereof substantially throughout.

9. The apparatus of claim 1 wherein means are provided for heating saidmold sections in the portions thereof which engage the parison toprovide the hinge to a temperature sufficient to plasticize thethermoplastic material.

References Cited by the Examiner UNITED STATES PATENTS 3,048,891 S/ 1962Maass 18-5 3,167,104 1/1965 Wiley et al 18-19 XR 3,242,245 3/1966 Greiget al 18-19 XR FOREIGN PATENTS 597,021 8/ 1959 Italy.

WILLIAM I. STEPHENSON, Primary Examiner.

WILBUR L. MCBAY, Examiner.

1. IN BLOW MOLDING APPARATUS FOR FORMING A THERMOPLASTIC CONTAINERHAVING MATING PARTS JOINED BY A HINGE WITH EACH PART BEING OF HOLLOWDOUBLE WALL CONSTRUCTION, MEANS FOR FORMING A TUBULAR PARISON OFTHERMOPLASTIC MATERIAL, MOLD SECTIONS ADAPTED TO BE MOVED INTOENGAGEDMENT ABOUT SUCH PARISON, SAID MOLD SECTION WHEN ENGAGED FORMING APARI OF CAVITIES ONE OF WHICH HAS THE SHAPE OF ONE OF THE CONTAINERPARTS AND THE OTHER OF WHICH HAS THE SHAPE OF THE OTHER OF THE CONTAINERPARTS, SAID MOLD SECTIONS ALSO ENGAGING THE PARISON ON OPPOSITE SIDESTHEREOF TO PINCH AND WELD THE PARISON BETWEEN SAID CAVITIES THEREBYPROVIDING THE HINGE AND DIVIDING THE PARISON INTO A PAIR OF HOLLOWSECTIONS WITHIN SAID CAVITIES, AND MEANS FOR INTRODUCING FLUID INTO THEPARISON SECTIONS TO EXPAND THE SAME INTO CONFORMITY WITH THE RESPECTIVECAVITIES.